Aircraft ski



F. J. DITTER AIRCRAFT SKI Jan. 31, 1956 5 Sheets-Sheet 1 Filed May 17,1952 INVENTOI? FRANCIS J. DITTER 7 9 BY ummy" F. J. DITTER I AIRCRAFTSKI Jan. 31, 1956 5 Sheets-Sheet 2 Filed May 17, 1952 INVENTOR III L I II I FRANCIS J. DITTER BY M4, am Jan. 31, 1956 F. J. DITTER 2,733,026

AIRCRAFT SKI Filed May 1'7, 1952 5 Sheets-Sheet 3 FIG. 3

nvvewron FRANCIS J. DITTER a! g Arron" Jan. 31, 1956 F. J. DITTER2,733,026

AIRCRAFT SKI Filed May 17, 1952 5 Sheets-Sheet 4 FIG.4

FIG.5

INVENTOR FRANCIS J. DITTER I BY w Jan. 31, 1956 F. J. DITTER 2,733,026

AIRCRAFT sx:

Filed May 17, 1952 5 Shae as-Sheet 5 O Q LL. g l mug-127 illll'll|iiiiil r'' .1: I I l 1 g In INVENTOR FRANCIS J. DITTER B) W manrmnun United States Patent" fiiice The present invention relates. to.a novel aircraft ski adapted to be employed in combination with theconventional wheel.- landing gear of an aircraft. The ski is adapted tobe actuated from the condition in which the wheel is in landing positionto the condition in which the ski is, in landing position. In addition,the. inven-. tion contemplates the. use of the landing wheel on top ofthe. ski such that thecompression of the tire on landing assists in theshock absorbing function.

It is therefore an object of the present invention to provide novelaircraft skis adapted to be employed. in conjunction with conventionalaircraft. wheel landing gear.

The following description of the invention will be with particularreference to the drawings in which Figure 1 is a perspective .view ofthe. forward portion of the'aircraft equipped, with the skis of the.presentinvention;

Fig. 2 is a sideelevation ofthe ski of'Figurel showing the skimounted'on the aircraft, the. latter being indicated in dotted lines;

Fig. 3 is a cross sectionalview of the ski taken through the mountingpedestallocated intermediate the ends of the ski;

Fig. 4 is a fragmentary side. elevation partly in section showing theski in landing position, the solid linesindicating the position of theparts at the moment of actual landing, the dotted lines indicating theposition of the parts during flight;

Fig. 5 is a. plan view of 'a the mounting pedestal;

Fig. 6 is a perspective showing detailsof the mounting and actuatingmechanism;

Fig. 7 is a side elevation showing the wheel in landing position;

' Fig. 8 is a fragmentary cross section. of the ski. illustrating theposition of the wheel. when the ski is retracted;

Fig. 9 is, a fragmentary cross. section. indicating. the

pos tion of the wheel withthe. ski in landing position portion of Fig.4. showing and the compression of the tire onthe ski at the pointoflanding; and

Fig. 10 is a fragmentary cross section showing position of the wheel.with-the ski in landing position, under flight conditions; and

Fig. 11 is a'fragmentary cross section showing a modification of theactuating arrangement.

With particular reference to. Figure l; the ski is composed of a baseshoe generally indicated at 11', which is curved both longitudinally andtransversely. The forward or toe portion of the base shoe 12 is curved,upwardlyas is the rear or heel portion 13. The base. shoe has a lateralportion 14 extending along the approximate forward half of the ski.There is provided, a flange 15 which is curved upwardly along theoutside edge of the lateral portion 14, andalong the inside edge of theski as shown inFig. 3..

Superimposedon the baseshoe is a' channel member 16 Eatented Jan. 31,1956 which has a generally inverted \I -Sha e-in cross section.Thischannel may be formed by rolling a piece of sheet stock. Accordinglythe base. 17 of the: V isav straight line longitudinally andis curved incross-section. A flangeis provided. at the. outward edges of the V for.suitable-fess tening such as riveting to thebase shoe. The ski may. beprovided with transverse reinforcing diaphragmslocated inside ofthechannel and being secured theretoand to the. base shoe. In theforward portion of the ski these reinforcingdiaphragms 18 extend fromthe outside of. the channel out over the; lateral: portion 14 of the.ski to. serve asadditional; support therefor. This; portion of the skiisprovided with. a suitable cover 19.

The ski is. attached tosthelanding gear by the. follow ing means. Atthe: intermediate portion of the ski the channel. ldis cutout and asaddle 20*is provided.- This saddle is shaped. to the general contour ofthe channel 16-but likewise has its central portion. cut out At the.sides of the saddle there are provided a. pair of pedestal members 22which may be seen in Figs. 2, 4 and 5; These pedestal members are.composed. of sheet members. suit-.- ably. attached to the saddle 20' bymeans of .flanges or legs 23 which extend downwardly along the saddle2i) and are, Welded thereto. These. pedestal. members are provided withopenings near. the top thereof for insertion of a boltor. pin24.

The actuating mechanism can best be seen withreference toFigs, 3 and 6.A tube:30;providedwitha bronze bushing 31 has attached to it ahydrauliccrank arm 32 and a skicrank .arm:33.- These are. suitablyattached to the tube 30, for example by welding. The. hydraulic crankarm. is. illustrated as a pair of arms; .while-the skicrank arm is.illustrated in Fig. 6v as, a built-up enclosed structure. At the. upperportion of the ski crank arm there is provided atransversestube-34:likewise provided with. a. bronze bushing 35. They tube 34 and thebushing 35. are adapted to. he slipped ontov a stub shaft 36 which issuitably attached at the end not shown to the inside. oithe, regularlanding wheel shaft. A pair: of

bearing washers, 37 and. 38 are employedand the bushing;

'sitepedestal member, and is held by. meansof nut, 41..

Suitable bearing washers. 42 and 43 are provided to. per.- mit the,entire ski assembly to rotate aboutthe pin.24.

' In Fig. 6 there is illustrated a bridging support member generallyindicated at 45. This bridging'rnember is composed of .a central. web.id-and. lateral flanges 47 and 48; The bridging support lower centralportion so that it may be placed in position over tube 3.0 after tube3.0 hasbeen. attached to the; pedestal supports. This bridging. membermay then be. bolted'down to the topv of pedestal member 20. The purposeof. this bridging member at the point at which the central portion ofthe ski has been cut out. By thus cutting out the'central portion of theski and providing. this bridging support member,.

member is cut out in the;

is essentially to add strength;

illustrated the actuating mechanism 3 for this hydraulic cylinder.tached at its outer end to the hydraulic crank arms 32 by means of bolt52. The piston arm is provided with an elongated slot 53 at its outerend through which the bolt 52 passes. The elongated slot permits thetire to be used as part of the shock absorbing mechanism. At the sametime this use of the tire to absorb shock has been accomplished withoutplacing any load on the hydraulic cylinder or the hydraulic system. InFig. 4 in the dotted lines will be seen the position of the wheel duringflight but when the ski has been lowered for landing. Under theseconditions the wheel bears lightly on the top of the lateral surface 14.It will be seen in the dotted lines of Fig. 4 that the pin 52 is nearthe inner end of the slot 53. In the solid lines in Fig. 4 will be seenthe position of the tire at the point of impact with the landingsurface. The tire is compressed to assume part of the load. As a resultof this compression the ski crank arm 33 has rotated counterclockwisefrom the dotted line position to the solid line position. The pin 52 haslikewise moved from the dotted line position to the solid line position,as has the piston rod 51. The slot 53 has permitted this movementwithout any longitudinal movement of the piston rod 51. Thus no changehas been made in the load on the hydraulic system by the impact oflanding.

In Figs. 7 and 8 is seen the relative position of the parts when thelanding wheel is in operative position. In Fig. 9 will be seen theposition of the parts at the point of landing on the ski. Fig. 10 showsthe relative position of the parts during flight when the ski is inlanding position.

In Fig. 2 is illustrated the means for regulating the ski by means ofcables so that it will assume a suitable attitude during flight. Forthis purpose there is provided near the forward end of the ski heavyelastic cables 60. These tend to keep the nose of the ski elevatedagainst the pull of the rear limit cable 61, which is a heavy steelcable, the purpose of which is to keep the nose of the ski from beingpulled up into contact with the airplane or into the path of thepropeller. The steel cable 62 provided ahead of the wheel is a limitcable which is normally slack, but which will keep the nose of the skifrom falling in the event that the elastic shock cable 60 is not able tomaintain it in normal flight level. At the rear of the ski is providedan auxiliary steel limiting cable 63 which likewise serves to keep thenose of the ski from rising too high.

When the plane is taxiing on the ski the compression of the tireprovides a small amount of slack in the limit cables to provide areasonable amount of pitching of the ski caused by unevenness of thelanding surface. During flight, however, the tire again expands and theski is held in proper attitude by the combination of the shock cord andthe limit cables.

In Fig. 11 there is illustrated a modification of the invention in whichthere is provided a single crank arm and the actuating means is attachedto this crank arm. The ski crank arm 33 has a hole passing therethroughin which bolt 60 is supported in the following manner. A spacer sleeve61 of greater length than the thickness of rod 51 is placed on bolt 60.This bolt is then passed through slot 53, washer 62 placed thereon, andthe bolt then passed through the hole in crank arm 33. A washer 63 andnut 64 hold the assembly together without frictional engagement alongthe sides of rod 51. This modification may necessitate some lateraladjustment of the mounting for the hydraulic cylinder as well as somecentering of the ski crank arm on the tube 30. This modificationprovides a simpler and less expensive structure for some installations.Other modifications may be made without departing from the spirit of theinvention. For example, the slot 53 may be placed in the lever arm foractuating the ski rather than in the rod 51. Likewise, mechanical stopsmay be provided to limit the movement The piston rod 51 is at- 4 of theski crank without the application of any additional load on thehydraulic system.

It will thus be seen that there has been provided a novel ski structurewhich may be mounted on the conventional aircraft landing gear, suchthat both the ski and the wheel may be in position at the same time. Inaddition, the ski is actuatable from the wheel landing gear to the skilanding gear. This may be performed during flight by means of controlslocated in the cabin. The ski is likewise provided with a lateralextension to the ski surface which serves to increase the landing areaand to provide a bearing surface for the wheel such that the compressionof the tire may be relied on for part of the shock absorbing structure.The actuating system is provided with a means which permits thiscompression without any load on the hydraulic system. Furthermore, theski is mounted inside of the wheel such that the ski is almost directlybeneath the landing gear structure instead of being laterally outwardlya considerable distance if the ski were placed outside the wheel.

I claim as my invention:

1. An aircraft landing ski adapted to be mounted on the wheel shaft ofan airplane comprising a single elongated landing surface, and a laterallanding surface extending outward along the forward portion thereof,means for attaching said ski to the wheel shaft of an airplane at theinner end of said wheel shaft such that the elongated landing surface isinside of the wheel and the lateral portion of said landing surface isin line with said wheel, a lever arm mounted on the ski and on the innerend of said wheel shaft, a second lever arm operable with said firstlever arm, means for operating said second lever arm including a rodhaving an elongated slot therein and being attached to said second leverarm by means of a pin passing through said slot.

2. An aircraft ski comprising a single elongated landing surface and alateral landing surface extending outwardly along the forward end ofsaid ski, and means for mounting said ski on an airplane such that theelongated landing surface is to one side of the wheel and the lateralsurface is in line therewith, means associated with said means formounting, for actuating said ski so that the landing wheel is lowermostin one position of said actuating means and so the ski is lowermost inanother position of said actuating means with the wheel positioned ontop of and in contact with said lateral surface.

3. An aircraft ski comprising an elongated landing surface, an invertedchannel member overlying said elongated surface and secured thereto, asaddle overlying said inverted channel, said channel and said saddlebeing cut out near the middle thereof, support means carried by saidsaddle for pivotally mounting said ski on a landing gear, said pivotalmounting being disposed below the base'of said inverted channel and alongitudinal removable bridging support member extending over saidpivotal mounting from a forward portion of the saddle to a rearwardportion of said saddle.

References Cited in the file of this patent UNITED STATES PATENTS401,429 Granger Apr. 16, 1889 1,757,687 Silva May 6, 1930 1,844,295Perry Feb. 9, 1932 2,106,934 Saulnier Feb. 1, 1938 2,261,751 BrintnellNov. 4, 1941 2,492,965 Carr Jan. 3, 1950 2,532,610 Ditter Dec. 5, 19502,532,611 Ditter Dec. 5,, 1950 2.539.817 Ditter Jan. 30, 1951 FOREIGNPATENTS 67,769 Germany Apr. 5, 1893 71,226 Sweden Feb. 24, 1931 181,436Germany Feb. 16, 1907

